Brush-holder assembly



BRUSHHOLDER AS'SEMBLY Filed Feb. 16, 1940 2 Sheets-Sheet l III/IMIIIIIIIIIIII WITNESSES: INVENTOR 6? FaymohaA/fchucK.

ATTORN EY March 10, 1942. R w SCHUCK 2,276,066

BRUSHHOLDER' ASSEMBLY Filed Feb. 16, i940 2 Sheets-Sheet 2 WITNESSES:INVENTOR ATTORNEY Patented Mar. 10, 1942 UNITED STATES PATENT OFFICEBRUSH-HOLDER ASSEMBLY Pennsylvania Application February 18, 16441,Serial No. 319,293

Claims.

The present invention relates to current-collecting devices fordynamo-electric machines, and more particularly to a brushholderassembly which is of simple and inexpensive construction.

Brushholders for dynamo-electric machines are usually pivotally mountedand spring means of various types are used to hold the brush against theslip ring or commutator with which it cooperates, so that the brushpressure is kept more or less constant as the brush wears down. Thistype of construction is subject to the difficulty that the brushholderoften tends to stick as a result of dirt or corrosion in the pivotalmounting. Such sticking is obviously very objectionable since it makesit impossible to maintain the desired brush pressure throughout the lifeof the brush, and it also makes it very difiicult to change or adjustthe brushes. Brushholder assemblies of this type are also usuallyrelatively complicated and are difficult to assemble on the machine withwhich they are to be used and to adjust to give the desired brushpressure.

The object of the present invention is to provide a brushholder assemblyof simple and ineX pensive construction which is very easy to assemblein a machine.

A further object of the invention is to provide a brushholder assemblywhich cannot stick because of dirt or corrosion on any part of theassembly.

A' still further object of the invention is to provide a brushholclerassembly in which the brush pressure is adjustable and in which suchadjustment can easily be made.

Other objects and advantages of the invention will be apparent from thefollowing detailed description, taken in connection with theaccompanying drawings, in which:

Figure 1 is an elevational view of a brushholder assembly, with parts insection;

Fig. 2 is a sectional View approximately on the line IIII of Fig. 1;

Fig. 3 is a perspective view of a brushholder, and

Fig. 4 is a perspective view of a supporting f block.

The invention is shown in the drawings as applied to a verticalalternating current machine having a shaft l and an upper end bracketZ.A cover plate 3 is secured in any suitable manner to the inside of thebracket 2, and the shaft passes through this plate and may be journaledin a bearing mounted in the plate. The cover plate 3 has radiallyoutwardly extending portions l at each side on which the parts of thebrushholder assembly are supported. Slip rings ii are mounted on theshaft and are connected to the rotor windings of the machine in anyusual or desired manner. It is to be understood that although a slipring motor has been shown Lil) in the drawings for the purpose ofillustration, the brushholder assembly of the present invention may beused equally well in cooperation with a commutator on either a directcurrent or alternating current machine.

The brushholder 6 of the present invention is shown in detail in Fig. 3and consists of a generally channel-shaped member of sheet steel, orother suitable material. The web portion of the channel is extended atone end of the brushholder and bent up to form a pivot l, while at theother end the web portion is cut out to provide an opening in which acarbon brush 8 may be secured by screws 9, or in any other desiredmanner. At the opposite end of the brushholder from the pivot 'l, theside Walls are brought together and clamped by means of rivets ID. Alead ll may be clamped under one of the rivets iii, as shown in Fig. 2.In the illustrated embodiment, three brushholders 6 are used, one foreach of the slip rings 6, and the leads II from the three brushholdersmay be connected to terminals l2 mounted on a terminal board it securedin any convenient position in the bracket 2.

The brushholders 6 are supported in position by a support block it. Theblock I l may be molded of any suitable insulating material and, asshown in Fig. 4, it is formed with three slots i5 for the reception ofthe three brushholders 6. The width of these slots is such that thebrushhoiders fit snugly in them. At one side of the block a ll-grooveIii is formed running at right angles to the slots 15. An extension i1is formed at one end of the block !4, and the block is mounted inposition in the motor by securing this extension to the end surface ofone of the extending portions 4 of the cover plate 3 by means of screwsl8, so that the block extends vertically dcwnward, as clearly shown inFig. 1. The brushholders 5 are inserted-in the slots is with theirpivots l engaged in the V- groove It so that they are free to move aboutthe pivots l to bring the brushes 8 into engagement with thecorresponding slip rings 5. It is to be noted that the brushholders arenot secured to the supporting block Hi in any way, but are merely placedin the slots, which restrain movement of the brushholders axially of theshaft, while permitting them to move freely about their pivots 1.

Spring provided to maintain the brushes 6 in engagement with the sliprings 5 under the desired pressure. th'i purpose a second support blockIii is prcvided on the opposite side of the shaft from the brushholders,and this block is secured to the extending portion 4 of the cover plate3 on that side of the motor by means of screws 2d. The block I9 ispreferably also molded of a suitable insulating material and has threeshallow grooves in each of which a spring support 2! is placed. Each ofthe spring supports 2! may consist of a piece of sheet metal having twoangularly related portions. One portion 22 fits into the slot of theblock W and is secured therein by means of screws 23, or in any othersuitable manner, while the other portion 24 of the spring supportextends outward from the slot beyond the shaft. This portion 24 of thespring support has three holes 25 in its end which serve as points ofattachment for a helical tension spring 25. The other end of the spring26 is secured in a hole 2? in the end of the brushholder 6, so that thespring tends to rotate the brushholder about its pivot l and thus holdsthe brush in engagement with the slip ring under a predeterminedpressure Three holes 25 are provided in the spring support 2i and theseholes are located at diiferent distances from the brushholder 6, so thatby moving the spring 25 from one of these holes to another a change inthe tension of the spring and therefore in the brush pressure may beobtained.

It should now be apparent that a brushholder assembly has been providedwhich is very simple and inexpensive, and which is very easy to assemblein position in the motor. In assembly, it is only necessary to placethebrushholders in the slots of the block Ml and to attach the springs 26between the brushholders and the proper holes 25 in the spring supports2! to give the desired brush pressure. It should also be particularlynoted that since the brushholder 6 is not secured to the block l4 in anyway, and since the pivot l merely engages in a V-groove in the block andis not fastened to it, it is impossible for the brushholder to stick nomatter how much dirt or corrosion may be present, but it will alwaysmove freely about its pivot, and thus the desired brush pressure willalways be maintained. The provision of the three holes 25 makes possiblea very easy adjustment of the brush pressure since it is only necessaryto unhook the spring 28 from one hole and hook it into another to changethe pressure. It will be understood, of course, that any suitable numberof holes 25 may be provided to give the desired number of adjustments.

Although a specific embodiment of the invention has been illustrated anddescribed, it is to be understood that its usefulness is not limited tothe particular embodiment shown, but that it may be used with any typeof motor having a rotary current carrying element for cooperation withbrushes, and that it may be used with any type of motor construction.The invention is not limited, therefore, to the exact details ofconstruction shown in the drawings and described above, but in itsbroadest aspects it includes all equivalent embodiments andmodifications which come within the scope of the appended claims.

I claim as my invention:

1. In combination with a dynamo-electric chine having a shaft with acurrent-carrying element thereon, a brushholder having a pivot at oneend thereof, a support member mount-ed at one side of the shaft, saidbrushholder being disposed in a slot in said support member with itspivot engaging in a V-groove in the support member, but not beingsecured thereto and being free to move about the pivot, a spring securedto the opposite end of the brushholder from the pivot, and a supportplate mounted at the opposite side of the shaft from the brushholder,one

end of said spring being attached to the plate to draw the brushholdertowards said current-carrying element.

2. In combination with a dynamo-electric machine having a shaft with acurrent-carrying element thereon, a brushholder having a pivot at oneend thereof, a support member mounted at one side of the shaft, saidbrushholder being disposed in a slot in said support member with itspivot engaging in a V-groove in the support member, but not beingsecured thereto and being free to move about the pivot, a spring securedto the opposite end of the brushholder from the pivot, and a supportplate mounted at the opposite side of the shaft from the brushholder,one end of said spring being attached to the plate to draw thebrushholder towards said currentcarrying element, said plate having aplurality of points of attachment for the spring to provide differentspring tensions.

3. A brushholder assembly for a dynamo-electric machine having arotatable current-collecting device comprising a support block at oneside of the current-collecting device. said support block having a slottherein extending transversely of the axis of the current-collectingdevice and a V-groove extending transversely of the slot, a brushholderdisposed in said slot, said brushholder having a pivot at one endthereof which engages in the V-groove of the support block, and springmeans attached to the brushholder at the opposite end from the pivot,said spring means tending to move the brushholder about its pivottowards the current-collecting device.

t. A brushholder assembly for a dynamo-electric machine having arotatable current-collecting device comprising a support block one sideof the current-collecting device, said support block having a slottherein extending transversely of the axis of the current-collecting device and a V-groove extending transversely of the slot, a brushholderdisposed in said slot, said brushholder having a pivot at one endthereof which engages in the V groove of the support block, a springsupport at the opposite side of the current-collecting device from saidsupport block, and a tension spring attached to said spring support andalso attached to the brushholder at the opposite end thereof from itspivot, said spring tending to move the brushholder about its pivottoward the current-collecting device.

5. A brushholder assembly for a dynamo-electric machine having arotatable current-collecting device comprising a support block at oneside of the current-collecting device, said support block having aplurality of parallel slots therein extending transversely of the axisof the currentcollecting device and a V-groove extending transversely ofthe slots, a plurality of brushholders disposed in said slots, each ofsaid brushholders having a pivot at one end thereof which engages in theV-groove of the support block. a plurality of spring supports at theopposite side of the current-collecting device from said support block.and tension springs attached to each brushholder at the opposite endthereof from its pivot and to a corresponding spring support. saidsprings tending to move the brushholders about their pivots toward thecurrent collecting device.

RAYMOND W. SCHUCK.

